Vagal Nerve Stimulation: Is It Effective in Children with Dravet Syndrome?

Dravet syndrome is a rare childhood epilepsy syndrome with an incidence of 1 in 40,000 births.1 Clinically, this syndrome is characterized by onset of recurrent febrile and afebrile seizures during the first year of life in a previously normal infant. Seizures are typically febrile, hemiclonic, or generalized, and are often prolonged with status epilepticus. Subsequently, myoclonic seizures, absence, and focal seizures appear between the ages of 1 and 5 years.2 Seizures can be provoked by slight temperature variations such as baths and physical exercise without true fever. Epilepsy is treatment resistant, and developmental delays are noted to occur inmost children to some degree.2 SCNIAmutations have been demonstrated in 85% of patients with Dravet syndrome.3 Status epilepticus, one of the core clinicalmanifestations of this condition, has been noted to be associated with developmental impairments.1,4 In addition, onset of absence seizures and myoclonic seizures early in life has been associated with worse cognitive outcome.5 There is a highmortality rate of 15 to 20% before the third decade of life6 in patients with Dravet syndrome due to status epilepticus and sudden unexpected death in epilepsy patients (SUDEP). Prevention of status epilepticus and attempts at better control of absence and myoclonic seizures may influence developmental outcome.4 However, treatment and control of epilepsy in Dravet syndrome is challenging. Although, antiseizure medications (ASMs) such as topiramate7 and combinations such as valproic acid, clobazam, and stiripentol8 are effective at controlling seizures in some patients, pharmacoresistant epilepsy is common. Stiripentol is not available in many countries, including the United States. Nonpharmacologic treatments for epilepsy including ketogenic diet, corpus callosotomy, and vagal nerve stimulation (VNS) are considered and used for management of medically refractory epilepsy.9 VNS does not carry the burden of cognitive and behavioral side effects which are common with antiepileptic medications. VNS can also improve quality of life and neuropsychologic performance.10 In children with Dravet syndrome who have a known predilection to cognitive decline,8 polytherapy with ASMs likely compounds the inherent neurocognitive impairments.11 Literature review revealed limited information to address the effectiveness of VNS in Dravet syndrome patients. There was only one case series with eight patients identified on PubMed search which suggested that VNS was effective in